Image transmission system with patterned data compression

ABSTRACT

A storage, retrieval, and transmission system is configured to provide fast, efficient telecommunication access to digitized images (e.g., medical diagnostic X-ray images) to multiple requesting subscribers. Image data are downloaded, via the telephone lines, to a remote display terminal in an optimal fashion that employs a two-dimensional patterned data compression scheme. The data compression methods include a &#34;Hex-Pac&#34; compression in which one first generates regions comprising a plurality of two dimensional, non-overlapping, symmetrically disposed super pixels that are collectively representative of an image. Each of these regions is subsequently compared with a plurality of fictitious patterns, each of which has a dark region, a light region and a predetermined point of origin, in order to determine which of the patterns most closely correlates with the selected region.

This application is a division of U.S. patent application Ser. No.07/915,298 which was filed Jul. 20, 1992 now U.S. Pat. No. 5,321,520

BACKGROUND OF THE INVENTION

Storage and retrieval systems for medical image data such as X-rayfilms, CAT scans, angiograms, tomograms and MRI are commonly antiquated.For example, when image films are used in the operating room, thephysician must display these photo films on a light box.

Moreover, due to the diffuse responsibilities of multiple attendingphysicians and treatment sites, image data for patients with complexconditions is often lost, or at best, difficult to find when needed.Hospitals maintain large "file rooms" to store bulky patient image datafilms. In a complex situation in which several folders are needed, afile's weight can build up to 7 kg. It has proven time consuming toobtain image data from file rooms due to administrative backlogs, tolack of specialized filing personnel and to misfiling.

Typically, the physician examines the patient in his office after theradiographical studies have been made in a hospital or diagnosticfacility. These films and the information contained therein are oftenunavailable at the time of the examination. Thus, there is a need forremote access to these image data for rapid patient assessment andtherapy recommendation.

U.S. Pat. No. 4,603,254 teaches a stimulable phosphor sheet carrying aradiation image stored therein scanned with stimulating rays. The lightemitted from the stimulable phosphor sheet in proportion to theradiation energy stored therein is detected and converted into anelectric signal converted to a digital signal. Digital data is createdto reproduce the radiation image for use in diagnosis and storage.

U.S. Pat. No. 4,764,870 describes a system for transferring medicaldiagnostic information from the diagnostic site to remote stations. Aninternal analog video signal from imaging diagnostic equipment such as aCAT scanner or MRI equipment, is converted to an analog video signal ofdifferent, preferably standard, format that is stored and transmitted inthe reformatted image information to the remote terminal. The receivedsignal is stored, decoded and applied in appropriate analog video formto an associated CRT display for reproduction of the diagnostic images.

U.S. Pat. No. 5,005,126 shows a system for transferring medicaldiagnostic information from the diagnostic site to remote stationssimilar to that found in U.S. Pat. No. 4,764,870.

U.S. Pat. No. 5,019,975 teaches a method for constructing a data base ina medical image filing system comprising the steps or recordinginformation indicating the time at which each medical image is recordedand a rank of importance for each medical image as image retrievalsignal data for image signals corresponding to each medical image;recording the number of times the image signals corresponding to eachmedical image have been retrieved as image retrieval signal data andincrementing the number each time the image signals are retrieved; andwhen the data base is full of image retrieval signal data, deleting theimage retrieval signal data corresponding to the image signals of themedical image in which at least (1) the time at which the medical imagewas recorded earlier than a predetermined time and (2) the rank ofimportance of the medical image is lower than a predetermined value.

U.S. Pat. No. 4,611,247 describes a radiation image reproducingapparatus to read a radiation image from a first recording medium as avisible image. Input devices of the apparatus enter data which areassociated with a method of exposing an object to a radiation andobject's exposed part. In response to the input data, a processingcondition determining unit determines conditions optimum for a gradationprocessing and a spatial frequency processing. A processor system isprovided for reading the radiation image stored in the first recordingmedium and processing the radiation image on the basis of conditionswhich the processing condition determining unit determines in responseto the input data associated with the radiation image.

U.S. Pat. No. 4,750,137 discloses a method and a computer program forperforming the method for optimizing signals being exchanged between ahost unit and an addressable-buffer peripheral device. The programoptimizes an outgoing signal from the host unit by (1) creating anupdated-state map representing the state of the peripheral device bufferexpected to exist after processing by the peripheral device of theoutgoing signal, (2) performing an exclusive-or (XOR) operation usingthe updated-state map and a present-state map representing the existingstate of the buffer, and (3) constructing and transmitting a substituteoutgoing signal which represents only changes to the buffer, and inwhich all premodified field flags are turned off. Position-dependentcharacters, such as attribute bytes, are translated into nondatacharacters prior to incorporation into a map, and are retranslated intotheir original form for use in the substitute signal.

U.S. Pat. No. 4,858,129 teaches an X-ray CT apparatus in which aplurality of dynamic tomographic images obtained by repeatedlyphotographing a region of interest of a subject under examination arestored in an image memory for subsequent display on a display device. Aprocessing device extracts data of pixels along a certain line common toall of the tomographic images and stores the pixel data in the imagememory, in the order of photographing time of the tomographic images,thus forming a time sequence image formed of picked-up pixels. Theprocessing device reduces a tomographic image and the time sequenceimage and rearranges the reduced images in one frame area of the imagememory for simultaneous display thereof on the display device.

U.S. Pat. No. 5,021,770 discloses an image display system having aplurality of CRT display screens. The system is of the type in which anumber of images of specific portions of a patient having a specificidentification code are selected from among a multitude of X-ray imagetaken by a plurality of shooting methods, and when the regions orinterest are specific, a plurality of appropriate images are furtherselected using the previously stored amplitude values for the regionsand shooting methods and displayed on the plurality of CRT displayscreens. In order that the segments to be inspected can be pointed to onthe screen on which the image of the patient is displayed, a memory isprovided which is adapted to previously store codes corresponding to thespecific image of the patient and to specify the respective regions ofthe image in such a manner that they correspond to the pixels positionsof the image.

U.S. Pat. No. 4,879,665 teaches a medical picture filing system composedof a picture data memory device, a picture data input-output device forinputting/outputting the picture data, a retrieving device for storingthe picture data into the memory device and extracting it therefrom onthe basis of retrieving data, a retrieving data input device forinputting the retrieving data into the retrieving device, a retrievingdata storing device for storing the retrieving data, the retrieving databeing classified by block of information obtained in one-timeexamination. When medical pictures are filed, retrieving data collectedfor each examination is utilized for reducing the amount of retrievingdata, while when reproduced, retrieval is carried out for each one-timeexamination thereby shortening the time required for retrieval.

In light of recent advances in computer data basing, digitization andcompression of image data, image enhancement algorithms and costeffective computer technology, the means for improved storage andretrieval of vital patient image data is now possible.

Such system should include the following major features:

1) means to more compactly store and more efficiently retrieve imagedata and automatically identify the data by patient name, image type,date and the like;

2) means for physicians to quickly and remotely access particularpatient image data at the medical facility even if archived at severaldifferent locations;

3) means to prevent loss of vital image data due to ordinary humanhandling and misplacement errors;

4) means to quickly and affordably access image data from thephysician's office;

5) means to enhance the medical images by both contrast enhancement andzooming for improved diagnostics and/or surgical guidance; and

6) means to quickly and conveniently access image data and display on alarge screen in the operating room with any desired enhancement orexpansion.

As described more fully hereinafter, the present invention providesmeans to accomplish these goals. The system uses both general purposesystem elements well known to those practiced in electronic arts andspecific elements having significant novelty.

SUMMARY OF THE INVENTION

The present invention relates to an automated high definition/resolutionimage storage, retrieval and transmission system capable for storing,transmitting and displaying medical diagnostic quality images for usewith medical X-ray films or the like.

The system comprises means to process the image data from patientimaging to physician usage. The major or significant processing stagesare described hereinafter. Specifically, the major steps in the imagedata flow include:

PATIENT RADIOGRAPHY: The patient's body is imaged and a film is exposedas in an X-ray room, MRI or CAT scan lab.

FILM PREPARATION: The film(s) is developed to create a visible imagewith OCR readable patient identification information superimposedthereon.

FILM INTERPRETATION: Commonly, a radiologist drafts an opinion letterfor the film(s). This document preferrably includes an optical characterreader, or OCR, readable patient identification label or standardmarking area.

IMAGE SCANNING & DIGITIZING SUBSYSTEM: A scanner subsystem digitizeseach patient image film and/or document on a high resolution scanner.This digitized data is transmitted by a local high speed data link to aseparate or remote master storage unit. Patient identificationinformation is read from a standard format on each file by OCRtechniques and efficiently stored with the digitized image data.Enhanced scanner resolution and gray scale requirements are provided.Further, to reduce data rate requirements, data compaction orcompression is accomplished within the scanner subsystem.

To back-up possible data link down time or scanner down time, thescanner subsystem may include a CD-ROM data storage drive so that imagedata may continue to be digitized. The CD-ROM disk may then be manuallydelivered to the file room unit for subsequent use.

In an optional embodiment, the digitized data of one or two images maybe written to a compact semi-conductor memory card "RAM Cards". Thisform of data storage may be used to send selected images for specialpurposes such as when the image data is needed in another city forsecond opinion purposes.

At this point in the image data flow, there is a split in which theoriginal film data is stored as a "master" in a file room and the imagedisk is made available for active "on-line" use in an image storage andretrieval subsystem.

FILM FILING: The patient image films may be placed in the industrystandard 14 by 17 inch brown paper folders and placed on conventionalfiling shelves. However, it is preferred that older films be tagged andstored off-site to reduce the current excessive bulk of films in manyhospital file rooms. The system would now make this practical since theoriginal films would seldom need to be accessed.

In the preferred embodiment of the system, the patient may have hisentire image data collected and written to one or more of the storageCD-ROM disks for archiving at the hospital.

IMAGE STORAGE AND RETRIEVAL SUBSYSTEM: This subsystem is a remotelycontrollable, automatically accessable image data subsystem to store andautomatically retrieve, on-demand, the compressed digital informationcontained on the CD-ROM disks.

The image storage and retrieval subsystem has a high-speed data linkconnection to the scanning and digitizing subsystem and has a writedrive recording mechanism which is dedicated to receiving the data fromthe scanning and digitizing subsystem. This CD-ROM write drive canoperate without interrupting remote access operations.

Remote access may be made to the image storage and retrieval subsystemby a variety of telecommunication links. Access will be granted only ifa valid user code has been presented. By means of several read-only CDdisk drives and electronic buffering, virtually simultaneous access canbe granted to several or more users.

As explained more fully hereinafter, the medical image disk will containrelatively huge quantities of data making it impractical to send overconventional data communication links without very efficient datacompression technology. While there are variety of data compressiontechniques available, none are well tailored to this application. Thus,novel compression means are in the remote telecommunication accesssubsystem.

TELECOMMUNICATION SUBSYSTEM: Occasionally circumstances may warrantmanually making an extra copy of the patient's image files to bephysically delivered to an authorized requester. However, for the systemto fulfill broad service to the health care industry it must be able toefficiently telecommunicate image files to remote locations both costeffectively and within a reasonable time interval.

A novel medical facsimile technology is in the preferred embodimentwhich works interactively with a remote requester to send only what isneeded at acceptable resolutions, and the presented image isprogressively updated as the communications connection is maintaineduntil the resolution limits of the user display are reached, after whichtime, other images are either sent or further enhanced.

The specific technical means for accomplishing this uses the followingnovel technologies: a) guided image selection & transmission (GIST); b)progressive image enhancement (PIE); c) display compatible resolution(DCR); d) hexagonal pattern classification compression (HexPac) and e)run length coding (RLC), RLC is well known to those skilled in the arts.

It appears practical to send immediately useful patient data in lessthan one minute over a phone line (9600 baud) whereas it take many hoursby conventional coding and transmission means. When wide-bandtelecommunications as satellite, fiber optic, micro-wave links becomesmore generally available at affordable prices, then the more complexdata compression techniques described here will be less important, butuntil that time, these types of techniques are believed essential tooverall system success.

This combination of technologies to efficiently compress the image dataand transmit remotely comprises the telecommunication access subsystem.In practice, these technologies may be implemented for the most partwith available computer modules although several special signalprocessor boards are needed.

REMOTE DISPLAY TERMINAL: The quality of the image available to the useris limited or determined by the receiving presentation terminal ormonitor. Two specific presentation terminal types are envisioned in thepreferred embodiment of the system, a modified personal computerterminal for use in a physician's office, hospital nurses' station andthe like, and a large screen presentation terminal with remotecontrolled interaction primarily for operating room use.

Both terminals have means to show the available patient directory ofimages, and means to select an image, enhancement and zoom on selectedareas. Image enhancement has heretofore been impractical for film basedimages and thus much subtle but important pathological information hasbeen largely lost. This is especially true of X-ray data. The ability toenhance subtle contrasted tissues areas is considered to be an importantfeature and benefit of the system.

An optional high-resolution printer (300 dpi or better) permits thephysician to print out selected images. This will be especially valuablewhen the physician expands and enhances selected critical image areassince a cost effective printer would otherwise not have adequate grayscale or pixel resolution to give diagnostically useful output.

Each terminal consists of a standard high performance personal computerwith one or more data source interfaces such as RAM card, CD-ROM disk ordata modem, a decompression graphics interface circuit and graphicsdisplay. The large screen presentation terminal has a large screendisplay for easy viewing for a surgeon who may be ten or more feetdistant. The large screen presentation terminal also has an optionalremote control so that an attending technician or nurse can scrollimages, enhance and zoom, at the surgeon's request.

A keynote of each terminal design is a very simple user interface basedupon a limited selection menu and obviously pointed-to graphical icons.

The invention accordingly comprises the features of construction,combination of elements, and arrangement of parts which will beexemplified in the construction hereinafter set forth, and the scope ofthe invention will be indicated in the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

For a fuller understanding of the nature and object of the invention,reference should be had to the following detailed description taken inconnection with the accompanying drawings in which:

FIG. 1 is a functional block diagram of the entire system of the presentinvention.

FIG. 2 is a functional block diagram of the image scanning anddigitizing means.

FIG. 3 is a functional block diagram of the image data storage andretrieval means.

FIG. 4 is a perspective view of the image data storage and retrievalmeans.

FIG. 5 is a functional block diagram of the telecommunication means.

FIG. 6 is a functional block diagram of the remote display terminalmeans.

FIG. 7 depicts the hexagonal pattern of the hexagonal compressionmethod.

FIG. 8 depicts an actual hexagonal pattern from an X-ray film.

FIG. 9 depicts the selected predetermined hexagonal pattern most closelycorresponding to the actual hexagonal pattern shown in FIG. 8.

FIG. 10 graphically represents the predetermined rotational orientationsfor the predetermined hexagonal patterns.

FIG. 11 graphically depicts a selected gray level slope of the selectedpredetermined hexagonal pattern of FIG. 9.

FIG. 12 depicts a single pixel from the predetermined hexagonal pattern.

FIG. 13 depicts a hexagonal pattern reconstructed by a remote displayterminal means corresponding to the actual hexagonal pattern shown inFIG. 8.

FIGS. 14-A through 14-H depict the predetermined set of orthogonal graylevel patterns.

Similar reference characters refer to similar parts throughout theseveral views of the drawings.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

As shown in FIG. 1, the present invention relates to an automated highdefinition/resolution image storage, retrieval and transmission systemgenerally indicated as 10 for use with medical X-ray film 12 or otherdocuments to provide simultaneous automated access to a common data baseby a plurality of remote subscribers upon request from the remotesubscribers.

The automated high definition/resolution image storage, retrieval andtransmission system 10 comprises an image scanning and digitizing means14 to transform the visual image from the medical X-ray film 12 or otherdocuments into digital data, an image data storage and retrieval means16 to store and selectively transfer digital data upon request, atelecommunication means 18 to selectively receive digital data from theimage data storage and retrieval means 16 for transmission to one of aplurality of remote visual display terminals each indicated as 20 uponrequest from the respective remote visual display terminal 20 through acorresponding communications network 21 such as a telephone line,satellite link, cable network or local area network such as Ethernet oran ISDN service for conversion to a visual image for display at theremote requesting site.

To improve automation and tracking, a machine readable indicia or label22 containing key patient information may be used in association withthe medical X-ray film 12. As shown, the machine readable indicia orlabel 22 is affixed to the medical X-ray film 12 prior to scanning bythe image scanning and digitizing means 14 to provide file access andidentification. Furthermore, digital data from alternate digitized imagesources collectively indicated as 24 and file identification may be fedto the image data storage and retrieval means 16 for storage andretrieval.

FIG. 2 is a functional block diagram of the image scanning anddigitizing means 14 capable of converting the visual image from themedical X-ray film 12 to digitized image data for transmission to theimage data storage and retrieval means 16 over a bi-directional highspeed data link 25. Specifically, the image scanning and digitizingmeans 14 comprises a film loading and scanning section and a datacompression and transmission section generally indicated as 26 and 27respectively and a display and control section generally indicated as28. The film loading and scanning section 26 comprises a film inputloader 30, alignment and sizing chamber 32, optical character reader 34and film scanner/digitizer 36 capable of at least 500 dots per inchresolution 36; while, the data compression and transmission section 27comprises a data buffer memory 38, low-loss data compression means 40,local data modem 42 and transmission connector 44 to operatively couplethe image scanning and digitizing means 14 to the image data storage andretrieval means 16. The low-loss data compressor 40 is also operativelycoupled to a compact disk data storage drive 46 capable of writing orstoring compressed digitized patient image data on a compact disk 48.The display and control section 28 comprises a keyboard/control console50, display terminal 52 and control computer 54 which is operativelycoupled to the other components of the image scanning and digitizingmeans 14 through a plurality of conductors each indicated as 55. A filmcollector tray 56 may be disposed adjacent the film scanner/digitizer 36to receive the medical X-ray film 12 therefrom following processing.

To reduce the approximately 238 Megapixels required to digitize a 14inch by 17 inch, medical X-ray film 12 with 700 dots or pixels per inchwith a two byte level to a manageable size without significantinformation loss, a linear gray level prediction, modified run-lengthcode generating logic circuitry is embodied within the low-loss datacompression means 40 to dynamically compress the digitized data beforestorage or recording. The image data is compressed with acceptablediagnostic resolution loss. The low-loss data compression means 40measures the "local" slope of the pixel gray level and continues tocompare that estimated gray level for up to an entire scan line until apixel region is reached which differs from the linear estimate by morethan a predetermined amount. The data actually sent for that regionconsists of the slope of the line, actual level at the origin of theslope line and the number of pixels comprising that region. Thecircuitry will discard linear gray level slope differences of theoriginal film which can be reliably determined to be noise or image"artifacts". A sudden one pixel (if at 1000 dots per inch) dramaticchange in gray level could be rejected as dust or film noise forexample. The compressed data is a trade-off between complexity, speedand minimum data loss to reduce the total data quantity stored by afactor of approximately three. Thus, about 80 Megapixels of data maystill have to be stored per 14 inch by 17 inch film image.

In the preferred embodiment, the bi-directional high speedcommunications link 25 transmits the low-loss compressed digitized datafrom the developing lab room to the hospital file room where the imagedata storage and retrieval means 16 will transfer and store the patientand image data in a new patient file on a compact disk 48.

Two way communications between the image scanning and digitizing means14 and the image data storage and retrieval means 16 minimizes data lossby insuring that a compact disk 48 be available to receive and storedata. Moreover, the compact disk data storage drive 46 with re-writableROM technology can record data even if communications with the imagedata storage and retrieval means 16 is disrupted. Thus the imagescanning and digitizing means 14 can automatically start writing data tothe compact disk data storage drive 46 as soon as a image data storageand retrieval means 16 fault is sensed. The display and control section28 informs the operator of the system status.

In operation, the film lab technician may stack one or more medicalX-ray films 12 onto the input loader 30 as shown in FIG. 2. A "read"button is depressed on the keyboard/control console 50 and each film 12is thereafter fed in automatically, digitized and transmitted to theimage data storage and retrieval means 16 located in the file room. Asthe reading of each film 12 is completed, the film 12 is deposited intothe film collector tray 56. System status, number-of-films read loggingand so forth are shown on the display terminal 52.

Initially, the image scanning and digitizing means 14 positions the film12 in the alignment and sizing chamber 32 on a precision carrying platenfor subsequent optical scanning. This platen contains optical sensors tosense the exact film size so only the useful image area is digitized.Once the film 12 is secured onto the movable platen, the film 12 ispassed through the optical character reader 34 and then to the filmscanner/digitizer 36.

The patient data and image identification is first recorded onto theremote CD-ROM file directory in the image data storage and retrievalmeans 16 from the OCR "pass" and then the compressed scanned image datais sequentially written to a compact disk 48 by a CD write drive forstorage with the CD library storage of the image data storage andretrieval means 16 as described more fully hereinafter as the film 12slowly passes through the film scanner/digitizer 36.

Specifically, the film scanner/digitizer 36 converts the image to adigital representation of preferably at least a 700 dot per inchresolution. This digital data is temporarily stored in the data buffermemory 38 where the patient data from the optical character reader 34and corresponding digitized image data from the file scanner/digitizer36 are properly formatted for subsequent compression and transmission tothe image data storage and retrieval means 16. The stored data is thenaccessed by and compressed by the data compression means 40 aspreviously described and transmitted through the local data modem 42 andtransmission connector 44 to the image data storage and retrieval means16 or a compact disk data storage drive 46. The display and controlsection 28 permits the X-ray lab staff to monitor system status, reportquantity of documents and films processed and allow for scheduling localrecording of image data on compact disks 48.

FIGS. 3 and 4 show the image data storage and retrieval means 16 toreceive and store the low-loss compressed digitized patient informationand image data from the image scanning and digitizing means 14 and toselectively transmit the stored low-loss compressed digitized patientinformation and image data to one or more of the remote visual displayterminal(s) 20 through corresponding telecommunication means 18 andcorresponding communications network(s) 21 upon request from one or moreof the remote display terminal(s) 20.

The image data and retrieval means 16 is essentially a central datastorage library for medical subscribers to remotely access and visuallydisplay patient data and information.

As described hereinafter, the image data storage and retrieval means 16is robotically automated to minimize hospital staff requirements. At anygiven time, it is estimated that a typical hospital may have severalhundred active patients with requirements for physician access tocorresponding image files. An active patient may require one to threecompact disks 48. Thus, the image data storage and retrieval means 16should have sufficient means to store and retrieve at least 500 compactdisks 48.

Further, to minimize personnel requirements, the image data storage andretrieval means 16 has a semi-automatic log-in mechanism for updatingthe compact disk inventory and an automatic mechanism for retrieving andreading the compact disks 48 remotely via communication link interfacessimilar to juke box playback mechanisms. Except for the occasionalloading of new empty compact disks 48 and removal of inactive compactdisks 48, the operation of the image data storage and retrieval means 16is fully automatic, permitting authorized access at any time.

As described more fully hereinafter, several playback drives withelectronic buffering are incorporated so that essentially simultaneousaccess can be provided to several remote requesting users. An optionalduplicating CD write drive and RAM-Card drive permits additional copiesto be made locally upon demand for either back-up or other use. Theimage data storage and retrieval means 16 has an operator's console/deskarrangement for file maintenance and duplicating control by the hospitalfile room clerk. Control software is a simple menu selection design sothat relatively unskilled personnel can maintain the central datastorage library or image data bank.

As shown in the functional block diagram of FIG. 3, the image datastorage and retrieval means 16 comprises a local data modem 58operatively coupled between the image scanning and digitizing means 14through the transmission connectors 44 and bi-directional high speedcommunication link 25, and a selector or multiplexer 60. A formatconvertor 62 is operatively coupled between the alternate digitizedimage source(s) 24 such as CAT 64, MRI 66 and/or video 68 and controlcomputer 70 which is, in turn, coupled to a control console 72 includinga visual display and input means such as a keyboard. The local data mode58 is also coupled to the hard disk (H/D) of the control computer 70through a conductor 71. The other components of the image data storageand retrieval means 16 are coupled to the control computer 70 through aplurality of conductors each indicated as 73. A CD write drive 74 isoperatively coupled between the multiplexer or selector 60 and an autodisk storage/retrieve mechanism 76 which is, in turn, operativelycoupled to a CD library storage 78, a manual load/purge box 80 and aplurality of data retrieval and transmission channels each indicated as81. Each data retrieval and transmission channel 81 comprises a CDreader drive 82 operatively coupled through a corresponding datainterface 84 to a corresponding transmission connector 86. In addition,one of the CD reader drives 82 is operatively coupled through a selectorswitch 88 to an optional CD write/RAM card drive 90 configured tomanually receive a compact disk 48 or RAM card.

As shown in FIG. 4, the CD library storage 78 comprises at least onecabinet 200 to operatively house 800 compact disks 48 arranged or fourshelves each indicated as 202 and the auto disk storage/retrievalmechanism 76 which comprises a CD coupler 204 to engage and grasp aselected compact disk 48 and move horizontally on a support member 206that moves vertically on a pair of end support members each indicated as208. An access door 210 permits movement of compact disks 48 to and fromthe cabinet 200. However, in normal operation, "old" patient data isremoved by writing collected image data to a single compact disk 48through the CD write/RAM card drive 90 thus freeing internally disposedcompact disks 48 for new data. The CD write/RAM card drive 90 may alsobe used to collect a patient's image data on a single compact disk 48for use in the operating room's display terminal. This obviates the needfor a high speed internal hospital local area network.

The computer associated with the CD robotic arm and drive mechanismperforms ordinary library maintenance functions such as retrieval ofoutdated files, access statistics, entry of access validation codes, andso forth. This computer subsystem also handles data communicationinterface functions.

Internal to the environmentally controlled cabinet 200 are a pluralityof playback mechanisms (field expandable to six) which are automaticallycontrolled by the accessing physicians via the coupled communicationssystem. Yet another CD-ROM write drive can record new data from theimage scanning and digitizing means 14 or perform library functions suchas consolidation of a patient's data from several compact disks 48 to asingle patient-dedicated compact disk 48.

The internal computer maintains a file log of which compact disks 48 areempty and where each patient's image data is stored by disk number andtrack on a disk location. When the image scanning and digitizing means14 requests to down-load data, the auto disk storage/retrieval mechanism76, of the image data storage and retrieval means 16 retrieves the"current" compact disk 48 which is being written with data (if notalready loaded), then loads the compact disk 48 into the CD write drive74, and signals to the image scanning and digitizing means 14 totransmit. Image data is then recorded with a typical record time of 4minutes for a full-size, high density image.

Once the robotic arm has delivered the compact disk 48 to the CD writedrive 74, the robotic arm is free to access and place other compactdisks 48 onto CD reader drive 82 as commanded by its communicationsinterface. The robotic arm can find and place a disk 48 into theappropriate CD reader 82 in approximately 10 seconds. Thus, there isminimal waiting time for disk access unless all CD readers drives 82 arein use.

As shown in FIG. 3, data is received through the input transmissionconnector 44 to the CD write drive 74 through the selector switch 60.Alternately, other image data from other sources such as CAT scanners 64or MRI medical equipment 66 may be fed through the format convertor 62for storage on a compact disk 48. If the other image sources are writtento CD write drive 74, file identification data must be supplied to theformat convertor 62 from the control computer 70.

The image file data received from the image scanning and digitizingmeans 14 is directly written to free space on a compact disk 48 in theCD write drive 74. No other data compression or special formatting isrequired as the image scanning and digitizing means 14 has performedthese functions. As new image data is received from the image scanningand digitizing means 14 or another image source 24, the image data issequentially appended to the last file on the compact disk 48 currentlybeing written to. Thus, no attempt is made to organize a singlepatient's image files onto a single compact disk 48. However, each filereceived is logged into the control computer 70 through the conductor71. Therefore, the control computer 70 always knows what disk locationin the CD library storage 78 contains any specified file. Once a compactdisk 48 is filled with image data, the auto disk storage/retrievemechanism 76 removes the compact disk 48 from the CD write drive 74 andstores the compact disk 48 in an empty location in the CD librarystorage 78.

The plurality of data retrieval and transmission channels 81 service thedata requests from subscribers. As previously indicated, a single dataretrieval and transmission channel 81 includes the select switch 88 todirect image file data to the optional CD write/RAM card drive 90. Bythis means, all image data for an individual patient may be collected onone or more selected compact disks 48 for archiving or other use.However, normally, the control computer 70 will automatically remove oldimage data by removing the compact disk 48 from the CD library storage78 and placing the compact disk 48 in the manual load/purge box 80. Theremoval age and exceptions information are selected by the systemoperator from the control console 72.

The control console 72 is also used to enter and maintain subscriberaccess identification codes in an "authorization file". This updateduser authorization file data is sent through a transmission connector 92to the telecommunications means 18 internal computer memory accessed bythe control computer 70 as needed to accept or reject subscriber datalink access requests. The user authorization file normally residing inthe telecommunications means 18 may be remotely updated by authorizedpersons.

The number of data retrieval and transmission channels 81 depends onintended subscriber demand. The image data storage and retrieval means16 is modular and may be upgraded as demand increases. Each datainterface 84 operates cooperatively with the telecommunications means 18to send only as much information as the telecommunications means 18 cancompress and transmit to a remote visual display terminal 20 of arequesting subscriber in a given time interval. Thus, the interface isan asynchronous block-buffered type.

Since the entire system 10 is designed to provide easy and quick accessto a patient's medical images, it is vital that these images betransmitted to a variety of locations in a timely and cost effectivemanner and further data compression is imperative. The telephone networkis still the most commonly available network but has a severe data ratelimitation of about 1200 bytes per second (9600 baud). While other highspeed telecommunication channels such as time-shared cable, satellitelink may eventually become commonly available, for the immediatelyforseeable future, the "phone" network must be used if system 10 is tobe practical today.

As noted earlier, a typical medical image may be stored as 119 megabytesof data. At 1200 bytes per second, it could take 27 hours to completelytransmit the already compressed medical image data. This is obviouslyunacceptable. To overcome this obstacle, the telecommunications means 18as shown in FIG. 5 utilizes five distinct data handling technologies toachieve useful data image transmission in less than one minute:

(1) Guided Image Selection and Transmission or GIST depends uponinteractive use by the physician to identify what portions of an imageare needed for enhancement or better resolution. Thus the data actuallytransmitted to the subscriber's visual display terminal 20 is guided bythe subscriber observing the image. In particular, once the user has animage displayed on his or her visual display terminal 20, the user mayoutline a specific region of interest such as a lesion or tumorousgrowth for more detailed study. The operator may select this regionusing a "mouse" or light pen or similar well-known computer displayterminal peripheral device. Having selected this region, the visualdisplay terminal 20 will display the more detailed pixel data be sent onthis region. The telecommunications means 18 will continue to sendfurther precision data until the natural resolution limits of thedisplay are reached or all available data is sent and received. Thisprocess of expanding an image region is known as "zooming" incomputer-aided design systems. The novel feature here is that the imageis further refined in resolution when "zoomed". The means for doing thisand knowing when to "stop" further pixel transmission is defined by thePIE and DCR technology described hereinafter,

(2) Progressive Image Enhancement or PIE utilizes the transmission timefrom the instant a first "crude" image is presented to the subscriber tothe present time of observation to progressively enhance the quality ofthe presented image. The longer the user observes a selected image, the"better" the image becomes in the sense of pixel resolution and quantityof gray levels. In the preferred embodiment, hexagonal pixel groups arefirst transmitted using the HexPac pattern compression technologydescribed hereinafter. Once a full terminal screen display has been madecomposed of these hexagonal patterns, then the telecommunications means18 transmits more precise pixel detail. First all pixels located on theperiphery of each hexagonal group are updated with their exact graylevel values and thereafter, all inner pixels are similarly updated. Ifthe display terminal's resolution is less than the 1000 dots per inch ofthe source image data, then pixel groups are sent, such as a square offour pixels, which match the display resolution and "zoom" expansionselected. This display matching technique is further defined hereinafteras DCR,

(3) Display Compatible Resolution or DCR transmits information about theuser's terminal 20 back to the telecommunications means 18. Only datawith a resolution compatible with that terminal 20 will be sent. Anyexcess data-link connect time can be used to send other image data whichis likely to be requested or has been pre-specified to be sent.

(4) An image pattern compression method comprising a Hexagonal PatternClassification or HexPac exploits the two dimensional nature of images.The data received by telecommunications means 18 is first uncompressedand placed into a multi-scanline digital buffer. This image data is thendivided up into hexagonal cells and matched against predefined patterns.Many fewer bits of data can be used to represent these predefinedpatterns, thus substantially compressing the image data for phone-linetransmission. The pixels of these hexagonal patterns may easily be"refined" by the PIE technology described earlier. If the DCR subsystemdetermines that the user terminal has a pixel area of, say, 1500 by 1000dots, then the HexPac technology recreates a new super pixel which isthe average gray level of all actual pixels within that super pixelarea. This immediately reduces the quantity of pixels to be sent (toonly 1500 by 1000 pixels). Without further data compression, thisquantity of data would still require about 26 minutes of datatransmission time at 9600 baud, the highest available phone network datarate.

(5) Run length coding or RLC permits data to be compressed by specifyinghow many pixels have the same gray level in a sequence or "run length"of scanning. The image data sent by a CD reader drive 82 totelecommunications means 18 is compressed with run-length coding but isnearly loss-less in the duplication of the original film data. Tosubstantially reduce the quantity of data needed to send an acceptablemedical image to a remote user terminal 20 over the data-rate limitedphone-line modem, a "lossy" compression is used. Since the PIE and DCRtechniques described earlier will eventually provide any degree ofdiagnostic image integrity desired, it is believed acceptable toinitially transmit a "lossy" image provided it gives adequate resolutionfor the user to begin the analysis and guided image selection. Manyfewer bits can describe this "run" of similar gray levels thuscompressing the amount of data sent. This technique is well known andoften used in facsimile transmission. A one dimensional RLC isincorporated in the preferred embodiment but since HexPac elements arebeing coded, it can be considered more accurately a quasi twodimensional RLC compression.

FIG. 5 is a functional block diagram of the telecommunications means 18including a control computer 94 operatively coupled to the image datastorage and retrieval means 16 through a transmission connector 96. Thevarious components of the telecommunications means 18 including a statuspanel 98 with a plurality of system indicators each indicated as 99 anda plurality of data compression channels each generally indicated as 100coupled to the control computer 94 by a plurality of conductors eachindicated as 101.

Each data compression channel 100 comprises a transmission connector 86,a communications data interface 102, a first compression processor ormeans 104 including logic means to generate the GIST and DCR datacompressions and corresponding first data memory 106, a secondcompression processor or means 108 including logic means to generate thePIE and HEXPAC data compressions and corresponding second data memory110 and a third compression processor or means 112 including logic meansto generate the RLC data compression and corresponding third data memory114, a corresponding modem 116 and a transmission connector 118.

The control computer 94 coordinates or controls data flow to and fromthe plurality of data compression channels 100 through the transmissionconnectors 86 and 118 respectively. Validated subscriber image datarequests are transmitted to the image data storage and retrieval means16 which searches the image library file 78 for availability of therequested compact disk 48. If available, the image data storage andretrieval means 16 loads the appropriate disk 48 from CD library storage78 into a CD reader drive 82 and informs telecommunications means 18through the transmission connector 96 to the control computer 94 that aspecific data interface 84 has data available to be transmitted throughthe corresponding transmission connectors 86. Once a subscribertransaction has been turned over to a specific data retrieval andtransmission channel 81, the data compression channel 100 receives thedata therefrom unless commanded to stop by a feedback control line. Thedata interface 102 is used to inform the CD reader drive 82 as to whatportion of the image is requested by the first compression means 104.Generally, the complete image is first requested. Thus the CD readerdrive 82 is requested to read the image data from the start.

The data is temporarily stored in the first data memory 106. Here thepixel data is first expanded from the RLC code into uncompressed pixeldata. This is only done on a relatively few number of scan lines--aboutone tenth of an inch height of original image data. This uncompresseddata is then remapped by the first compression means 104 into "larger"pixels whose average intensity is the average of all combined pixelscompatible with the display resolution receiving remote visual displayterminal 20. This "super pixel" data is then fed to the second datamemory 110. The super pixel data in memory 110 is then processed by thesecond compression means 108. Initially, the lowest resolution imagewill be transmitted to rapidly form a useful remote image on therequesting remote visual display terminal 20 through a communicationsnetwork 21. This will be done by combining super pixels in the seconddata memory 110 into hexagonal patterns which approximate the group ofsuper pixels. These HexPac data packets are then sent to the third datamemory 114. There the HexPac data packets are further compressed by thethird compression means 112. These packets of run-length coded HexPacdata packets are then transmitted through the corresponding modem 116and transmission connector 118 over the selected communications network21. The modem 116 includes state of the art error control techniquessuch as block retransmission when a remote error has been detected.Thus, data transmission is essentially error-free as needed forcompressed data handling.

The control computer 94 includes circuitry means to monitor the activityof each data channel. The identification of each subscriber is loggedalong with the total connect time for billing purposes. Thus the controlcomputer 94 generally coordinates the plurality of communication linksand their connections to the particular data retrieval and transmissionchannel 81 within the image data storage and retrieval means 16 as wellas granting access and performing connection accounting tasks. Thestatus panel 98, connected to the control computer 94 is used to aide insystem debug and indicate operation of the data compression channels100. The status panel 98 would not normally be used by hospitalpersonnel but by system service technicians.

The control computer 94 also has a permanent memory such as a hard diskto record subscriber usage data and internally sensed hardware problems.This data may be downloaded on any of the transmission connectors 118when a correct authorization code has been received. Thus, the servicingcompany can acquire subscriber usage information remotely for billingpurposes and system diagnostic purposes.

The preferred embodiment of the telecommunications means 18 uses modularcommunication channel hardware. Thus, the module may be customized tofunction with any type of communication channel such as satellite links,cable networks or a local area network such as Ethernet or ISDNservices.

It is important to note that all communications is bidirectional so thatif, say, a remote visual display terminal 20 should become temporarily"overloaded" with image data due to decompression processing delays ordue to a detected data error, then, the remote visual display terminal20 may request that data transmission be stopped or a block of data berepeated until it is received correctly.

FIG. 7 graphically shows a hexagonal group of the hexagonal compressionmethod comprising a group of square image pixels partitioned into ahexagonal group. The pixels are numbered for convenience of referencefrom the inside to the outside in a clock-wise manner. Each hexagonalgroup or packet comprises 24 super pixels as earlier described but othernumbers are possible. It is assumed that each pixel is gray level codedusing 2 bytes of data. Thus, the hexagonal group requires (24×2) 48bytes of data to fully represent the 24 super pixels comprising theimage pattern at the user terminal 20.

FIG. 8 shows a typical pattern as may occur in a region of an X-ray film12. The method predefines a group of likely patterns, one of which isrepresented as a "best" match as in FIG. 9 with the actual pattern inFIG. 8. As shown in FIGS. 14A through 14H, there are 8 possiblepredetermined representative gray level patterns represented by 3 bits.These patterns are specifically selected to be essentially uncorrelatedwith each other even if rotated relative to each other. As shown in FIG.10, these patterns may be rotated through 8 equal angles (another 3 bitsof data) to best match the actual pattern. Rotation angle "1" is shownin FIG. 10 as the best match for the given example. Thus far, six bitshave been used to approximate the actual pattern of FIG. 8. As shown inFIGS. 14A through 14H, each fictitious pattern includes a dark and lightregions and origin. Although FIG. 11 discloses a straight gray levelslope corresponding to the pattern shown in FIG. 14A, the gray levelslope will vary with the fictitious pattern. For example, the gray levelslope of the fictitious pattern shown in FIG. 14D would closelyapproximate a V shape.

FIG. 11 shows how the gray level slope may be discretely selected tobest match the slope of the actual pattern. Two bits are used toapproximate this slope.

FIG. 12 shows that one particular pixel, such as the darkest pixel, hasbeen selected to be fairly precisely gray level represented by means of8 bits (256 gray levels).

The total bits required to approximate the actual pattern is 16 or twobytes. FIG. 13 shows how this fictitious or reconstructed pattern may bereproduced at the user terminal 20 when decoded.

In this example, only two bytes were required to represent "adequately"an original 48 bytes of image data. Thus, a 24 to 1 compression ratiohas been achieved. Further, run-length encoding (RLC) may be used onthese HexPac groups to further reduce redundant spans of white andblack. It is estimated that the combined compression ratio of HexPac andRLC on the super-pixel image is about 36 to 1 for this particular set ofparameters. This combined compression technology reduces datatransmission time (at 9600 baud) to approximately 43 seconds for aninitial useful medical image.

For medical images, further enhancements through the PIE compressionshould favor the elimination of artificial lining between hexagonalpatterns first. As the user continues to view the same image, then thePIE compression will progressively improve the gray level integrity byupdating all number 24 pixels to 8 bits of gray level resolution andupdating all number 23 pixels to 8 bits of gray level and so forth forall remaining pixels in descending order. This process takes about 10minutes at 9600 baud to update all peripheral hexagonal pixels and about20 minutes total for all pixels.

If the user continues to observe or request further image resolution,the telecommunication means 20 causes each pixel gray level to beupdated by one additional bit in descending order again until the full16 bits of gray level is received and stored at the terminal 20 for eachsuper pixel. Each doubling of gray level resolution takes between 1 and2.6 minutes at 9600 baud depending on the run length statistics of thegray levels.

FIG. 6 is a functional block diagram of a remote visual display terminal20 to be operatively coupled to one of the data compression channels 100of the telecommunication means 18 by a communications network 21 and atransmission connector 118. The visual display terminal 20 comprises adata communications modem 120 operatively coupled to a control computer122 and RLC decompression means 124. The RLC decompression means 124 is,in turn, operatively coupled to a memory 126, a PIE bypass 128 and apattern select and modifier 130 which is operatively coupled to a HexPacpattern ROM 132 and the control computer 122. A memory 134 isoperatively coupled between the PIE bypass 128 and pattern selector andmodifier 130 and a display drive 136 which is operatively coupled to animage display 138. In addition, an image enhancing processor means 139including circuitry to generate edge contrast enhancement, gray levelcontrast enhancement by means of gray level region expansion ordifferential gray level tracking and gray level enhancement or otherstate of the art image enhancement method well known to those skilled inthe art. The control computer 122 is operatively coupled to an interface140 to a first control or selector means 142 and a second control orselector means including a radio receiver 144 and signal command decoder146 for use with portable keyboard transmitter 148. In addition, anoptional CD read/write drive 150 may be provided for use with a compactdisk 48.

The modem 120 has built-in compatible error correction technology tocommunicate with corresponding transmitting data compression channel100. After the user has selected the image data storage and retrievalmeans 16 and validated authority by swiping through an identificationmagnetic card 152 or otherwise through a magnetic card reader 154entered an assigned security code, the operator may select a patient andone or more image files presented to him on the display screen 138.Selection is accomplished by a touch-screen overlay on the first controlor selector means 142 or by the keyboard transmitter 148 of the secondcontrol or selector means.

Once one or more images have been selected by the user, the modem 120writes image data to the temporary memory 126 which is actively accessedby the RLC decompression means 124. This decompressed data describes theHexPac patterns or packets as stripes of the image running, for example,sequentially from left to right. These Hexpac pattern specifications,typically 2 data bytes or 16 bits are then routed to a pattern selectionprocessor 130 which accesses the predefined patterns from Read-OnlyMemory device 132. Each pattern is then rotated and gray-level modifiedby processor 130 according to the HexPac 16 bit pattern specificationreceived from the RLC decompression means 124. Each modified pattern isthen written to a graphics display memory circuit 134. As the graphicsdisplay memory circuit 134, develops the pattern data, the displaydriver 136 and image display 138 show the image on the screen as it isreceived. In this manner, the entire "first pass" medical image ispainted on the image display 138 screen.

If the user makes no further intervention, then once the image is fullydisplayed on this "first pass", then the progressive image enhancementtechnology requests pixel enhancement data. This enhancement databypasses pattern selector and modifier 130 and is routed through the PIEbypass 128. In the PIE bypass 128, the enhanced pixel information isdirected to the correct graphic memory locations in the graphics displaymeans circuit 134'. Thus, the display driver 136 and image display 138are continually resolution enhanced.

If the image is fully enhanced to the limits set by the DCR in thecontrol computer 122, the image storage and retrieval means 16 isdirected by the control computer 122 to begin sending new image data onthe next selected image and begin storing this image data in a secondgraphics display memory circuit 134". This second data memory 134" canhold one or more images and may be selected immediately by the user whenhe is finished inspecting an earlier image. The user may further directby touch screen command 142 that these be stored in the computer's harddisk or archived by the optional CD read/write drive 150.

The user may at any time select a portion of the displayed image forfurther expansion by enabling or selecting the Guided Image Selection &Transmission (GIST) circuitry in the control computer 122 or imageenhancement through the image enhancing processor means 139. This may beaccomplished either by touch screen control means 142 or the secondremote control means 144/146/148. This remote keyboard and transmitterunit 144/146/148 duplicates the on-display simulated push-buttons of thetouch screen control means 142. Coded command signals sent by 148 arereceived by radio receiver 144 and decoded by 146. These commands arethen accepted by control computer 122 as though they were normalkeyboard commands.

The user may terminate a session with the image data storage andretrieval means 16 at any time by selection of stop and escape command.While a printer is not shown in this description, it can be an optionaladdition to terminal 20.

In summary, the image data storage and retrieval means 16 selects thefirst image and writes that data to a temporary memory buffer in thetelecommunication means 18. Information about the subscriber's terminalis uploaded to the telecommunications means 18 so that the DisplayCompatible Resolution (DCR) logic circuitry knows when to stop sendingadded data for the requested first image. A special interactivecompression computer then compresses this first image data using theHexPac circuitry and sends that data over the data link modem to thesubscriber terminal 20. Error detection and correction methods willgenerally be used in this communications link protocol.

Once a first "crude" image is sent to the subscriber visual displayterminal 20, then the Progressive Image Enhancement (PIE) circuitrybegins to send additional data to further refine the resolution of eachhexagonal pixel region. If no further guidance is given by thesubscriber, the PIE will continue to refine the picture's resolutionuntil its natural limit is sent for the terminal 20. Thereafter, the PIEwill begin sending image data from the second specified film and loadingit into yet another memory buffer. Thus, the data link connection isalways transmitting useful data even though the subscriber may only beanalyzing one image for some time.

However, should the user desire to zoom in on a particular region of animage, he or she may define that region desired on the terminal 20 bythe Guided Image Selection & Transmission (GIST) to expand the visualdisplay accordingly. The DCR will recognize the requirement foradditional resolution and command the PIE to begin transmittingadditional pixel information until such time as the DCR informs it thatonce again the natural display resolution limit has been reached.

The following image enhancement means present in the instant invention:edge contrast enhancement, gray level constrast enhancement by means ofgray level region expansion or differential gray level tracking and graylevel enhancement and may be accomplished by the image enhancingprocessor means 139 in the visual display terminals 20.

The human eye cannot reliably discern gray level differences less thanapproximately 2%. Yet, significant tissue density information causesX-ray gray level differences in this range and below. The enhancementtechnologies above will cause these tissue density differences to bemagnified thus revealing hitherto unseen image data.

To ensure ease of use, the following features are incorporated:touch-screen selection of commands, magnetic card identification of thesubscriber or user, icon based menus or selection buttons on the CRTdisplay and split image display screen overlays.

It will thus be seen that the objects set forth above, among those madeapparent from the preceding description are efficiently attained andsince certain changes may be made in the above construction withoutdeparting from the scope of the invention, it is intended that allmatter contained in the above description or shown in the accompanyingdrawing shall be interpreted as illustrative and not in a limitingsense.

It is also to be understood that the following claims are intended tocover all of the generic and specific features of the invention hereindescribed, and all statements of the scope of the invention which, as amatter of language, might be said to fall therebetween.

Now that the invention has been described,

We claim:
 1. An image storage, retrieval and transmission systemcomprisingmeans forming an initial digitized image, computer meansstoring said digitized image, telecommunication means linking saidcomputer means to a remote visual display terminal, saidtelecommunication means comprising compression means including logicmeans togenerate a plurality of regions collectively representative ofsaid image, each said region comprising a plurality of two dimensional,non-overlapping, symmetrically disposed supper pixels and to compareeach said region with a plurality of fictitious patterns, each saidpattern having a dark region, a light region and a predetermined pointof origin, and thereby to determine which of said plurality offictitious patterns most closely correlates with said region and togenerate a compressed digitized representation corresponding to saidselected fictitious pattern, and wherein said remote visual displayterminal includes means to generate and display an image correspondingto said fictitious pattern.
 2. A system of claim 1 wherein saidfictitious patterns are selected to be essentially uncorrelated witheach other when rotated relative to each other.
 3. A system of claim 2further including logic means to select a fictitious pattern having agray level most closely correlated with a gray level of a said superpixel.
 4. The system of claim 1 wherein said means forming an initialdigitized image comprises a format converter having a digital videosignal as an input.
 5. The system of claim 1 wherein said means formingan initial digitized image comprises a medical X-ray film and an imagescanner.
 6. A system of claim 1 wherein said compression means furtherincludes logic means to determine which of said plurality of fictitiouspatterns most closely correlates with said region and to generate acompressed digitized representation corresponding to said selectedfictitious pattern, and wherein said remote visual display terminalincludes means to generate and display an image corresponding to saidfictitious pattern and means to rotate a said selected pattern to thatone of a plurality of predetermined rotational orientations that mostclosely approximates said super pixel.
 7. A system of claim 1 whereinsaid remote visual display terminal includesmeans to generate anddisplay an image closely correlated to said actual super pixels inresponse to receiving said compressed digitized image data correspondingto said selected fictitious patterns and logic means to generate a setof predetermined representative gray levels wherein each said gray levelis that one most closely correlating with the gray levels of said actualsuper pixel.
 8. A system of claim 7 wherein said terminal means furthercomprises logic means to rotate a said selected pattern to that one of aplurality of predetermined rotational orientations that most closelyapproximates said actual super pixel.
 9. A system of claim 1 whereinsaid telecommunication means further includes means to compress andtransmit to said remote terminal digitized image data specific to aselected sub-image and wherein said remote terminal further comprisesmeans to provide a visual display of said selected sub-image.
 10. Asystem of claim 9 wherein said compression means further includesprogressive image enhancement means transmitting, subsequent to adisplay of a said selected sub-image, data representative of exact graylevels of those super pixels located on a periphery of each regionwithin said selected sub-image and thereafter transmitting similar datafor those super pixels interior to each said region, whereby theresolution of said displayed sub-image increases with time.
 11. A systemof claim 10 wherein said terminal has a resolution limit, wherein saidterminal comprises means to communicate said resolution limit to saidtelecommunication means, and wherein said telecommunication means sendsno additional data if the resolution of said displayed sub-image isequal to said resolution limit.
 12. A system of claim 1 wherein saidcompression means further includes run length compression of saidfictitious patterns.
 13. A system of claim 1 wherein said remote visualdisplay terminal further includes image enhancement means to enhance adisplayed image.
 14. A system of claim 13 wherein said image enhancementmeans includes logic means to enhance an edge contrast of a displayedimage.
 15. A system of claim 13 wherein said image enhancement meansincludes logic means to enhance gray level contrast by means of graylevel region expansion.
 16. A system of claim 13 wherein said imageenhancement means includes logic means for differential gray leveltracking and gray level enhancement.
 17. A system of claim 1 whereinsaid telecommunication means further comprises means to enhance the grayscale of a said image,means to transmit to said terminal a first datablock usable to reconstruct a said image without said enhancement, andmeans to transmit to said terminal a second data block usable toreconstruct said image with a said enhanced gray scale.
 18. A system ofclaim 1 wherein said compression means further includes progressiveimage enhancement means transmitting, subsequent to a display of a saidimage, data representative of exact gray levels of those super pixelslocated on a periphery of each region within said image and thereaftertransmitting similar data for those super pixels interior to each saidregion, whereby the resolution of said displayed image increases withtime.
 19. A system of claim 18 wherein said terminal has a resolutionlimit, wherein said terminal comprises means to communicate saidresolution limit to said telecommunication means, and wherein saidtelecommunication means sends no additional data if the resolution ofsaid displayed image is equal to said resolution limit.
 20. A method ofacquiring, storing, retrieving and displaying an image comprising thesteps ofa) acquiring a said image having a first resolution, andtranslating said image to a predetermined digital format, b) storingsaid digitized image in a computer memory at a first location, c)requesting, from a user-operated terminal having a first resolutionlimit and located at a second location, a said digitized image, d)creating from said digitized image, at said first location a patternedand compressed representation thereof by means of a hexagonal patternclassification algorithm comprising the steps ofd1) generating aplurality of regions collectively representative of said image, eachsaid region comprising a plurality of two dimensional, non-overlapping,symmetrically disposed super pixels, d2) comparing each said region witha plurality of fictitious patterns, each said pattern having a darkregion, a light region and a predetermined point of origin, d3)selecting that one of said plurality of fictitious patterns that mostclosely correlates with said each said region, e) transmitting from saidfirst location to said terminal a first portion of said stored patternedrepresentation, f) reconstructing, at said terminal, by means of asecond algorithm, from said first portion of said patternedrepresentation, a first displayable representation of said diagnosticimage, said first displayable representation having a second resolutionless than said first resolution, and g) displaying said displayablerepresentation at said terminal.
 21. The method of claim 20 furthercomprising the steps of:h) transmitting from said first location to saidterminal an additional portion of said patterned representation, i)reconstructing, at said terminal, by means of a third algorithm, fromsaid additional portion of said patterned representation, an improveddisplayable representation of said image, said improved displayablerepresentation having a third resolution greater than said secondresolution, j) repeating steps g), h) and i), thereby progressivelyincreasing the resolution of said displayed representation until saiddisplayed resolution attains the lesser ofsaid first resolution of saidimage or said predetermined resolution limit of said terminal.
 22. Amethod of claim 21 further comprising an additional step before step h)of defining, by means of a user-operated computer-interactive device, asub-image of said visual representation, and wherein said subsequentreconstructions in step j) are directed at reconstruction only of saidsub-image.